How to modify the class "Array" in Ruby?

Question

I'm new about ruby! I just wanna do the following:

module Functional
  def filter
  end
end

class Array
  include Functional
  def filter
  end
end

a = [1, -2, 3, 7, 8]
puts a.filter{|x| x>0}.inspect      # ==>Prints out positive numbers

How could I modify the method "filter" in Array? Could anybody help me? Thank you

Try to create a reproduction test-case on ideone.com or similar (against a specific Ruby version, ideone is currently Ruby 1.9.3) so the behavior can be verified - for instance, when I try, I get nil as output . Counterexample? :) — user2864740
– user2864740, Commented Nov 14, 2013 at 5:25

sawa · Accepted Answer · 2013-11-14 05:45:41Z

2

class Array
  alias filter :select
end

a = [1, -2, 3, 7, 8]
a.filter{|x| x > 0}

answered Nov 14, 2013 at 5:45

sawa

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Comments

inertialgradient · Accepted Answer · 2013-11-14 05:32:03Z

1

I think what you're looking for is this:

module Functional
  def filter
    return self.select{ |i| i > 0 }
  end
end

class Array
  include Functional
end

a = [1, -2, 3, 7, 8]
puts a.filter{|x| x>0}.inspect      
#=>[1, 3, 7, 8]

Although I think you can save yourself the trouble by just using select -- there's no need to reimplement it.

answered Nov 14, 2013 at 5:32

inertialgradient

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1 Comment

MxLDevs Over a year ago

Oh, the comment was what OP wanted to do, not what OP was seeing and wondering why it wasn't being re-defined.

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